No person shall make any alteration to any premises in which a gas fitting or gas storage vessel is fitted if that alteration would adversely affect the safety of the fitting or vessel in such a manner that, if the fitting or the vessel had been installed after the alteration, there would have been a contravention of, or failure to comply with, these Regulations.
No person shall do anything which would affect a gas fitting or any flue or means of ventilation used in connection with the fitting in such a manner that the subsequent use of the fitting might constitute a danger to any person, except that this paragraph does not apply to an alteration to premises.
In relation to any place of work under his control, an employer or a self-employed person shall ensure, so far as is reasonably practicable, that the provisions of paragraphs (1) and (2) above are complied with.